For as long as I can remember, I've been having issues with scrolling in Windows and its applications. When scrolling via dragging the scroll blob, it seemed as if Windows had the annoying habit of randomly resetting your scroll blob to its starting position, which irritated me to no end. It took me a while to figure out, but I finally know when this behaviour occurs - now I just need to know: why?!

Yep - All X-based UI systems (like KDE or Gnome) treat the mouse wheel event the same way they treat other mouse events - they go to the window underneath the cursor. Mac OS X behaves the same.

Windows treats it as a key press event, so it goes to the active window. Not only that, but it goes to the active control. If you have a window with multiple scrollable controls (Windows Explorer, for example, or a web page with an iframe in it) you have to click first to select the control, then scroll.